It's maybe a bit late but...
.dat file - is just metadata of language pack(language, author, mb icon). You set these in compiler.
Just use AuroraLanguagePackCompiler or "Compile" button in AuroraTranslationTool. However, it didn't worked for me for some reason, neither newer version of AuroraLanguagePackCompiler somewhere on this forum. So I just built it from source(https://github.com/XboxUnity/AuroraLanguagePackCompiler) and it worked for me on Aurora 0.7b.
Attached archive with it to this post
AuroraLanguagePackCompiler.zip